Does occupational noise exposure aggravate age-related hearing loss? A population-based study.

PURPOSE: To determine whether occupational noise exposure aggravates the progression of age-related hearing loss and to analyze frequency-specific annual threshold shifts. METHODS: We analyzed cross-sectional data from 3,719 participants (aged ≥ 40 years) in the 9th Korea National Health and Nutrition Examination Survey (KNHANES, 2023). Occupational noise exposure was defined as working in an environment with loud noise for ≥ 3 years. Linear regression with an interaction term (age × noise exposure) was used to compare the annual rate of threshold deterioration (dB/year) for each frequency. RESULTS: The noise-exposed group (n = 617) showed worse hearing thresholds than the unexposed group (n = 3,102) across all ages. Across frequencies, the largest absolute threshold difference between groups was observed at 4 kHz (10.0 dB, p < .001). Among frequencies, 2, 4 and 8 kHz were significantly associated with noise exposure after adjusting for age, sex, educational level and household income, with 4 kHz being the most prominent (OR per 1 dB increase, 1.020; 95% CI, 1.014-1.025). Age-related hearing decline was steeper in the noise-exposed group than in the unexposed group (excess shift of 0.10 dB/year, p = .008). In frequency-specific analysis, the noise-exposed group showed the largest excess annual hearing decline at 2 kHz (0.17 dB/year, p < .001) and 4 kHz (0.17 dB/year, p = .005), followed by 1 kHz (0.09 dB/year, p = .034). CONCLUSIONS: Occupational noise exposure was associated with a poorer hearing and a steeper age-related widening of the threshold gap versus unexposed individuals, most prominently at 2 and 4 kHz. These findings underscore the need for clinicians and hearing conservation programs to focus on 2 and 4 kHz thresholds when monitoring noise-exposed workers.